Imaging system, imaging method, and computer program

ABSTRACT

An imaging system includes: an imaging unit that captures an image of an eye area of a target person by using an image sensor that allows imaging without saturating observed light; an acquisition unit that obtains, from the image, a first information about a first area that does not include reflection of light by an eyeglass lens of the target person, and a second information about a second area that includes the reflection of the light; and a correction unit that corrects the second information so as to reduce an influence of the reflection, on the basis of the first information. According to such an imaging system, it is possible to properly capture the iris image even when the target person is wearing eyeglasses.

TECHNICAL FIELD

This disclosure relates to an image imaging system, an imaging method,and a computer program that image an eye area of a target person.

BACKGROUND ART

A known system of this type applies light around an eye of a targetperson to capture an iris image. For example, Patent Literature 1discloses a technique/technology of photographing by applying light toan eyeball at an incident angle, and of sequentially applying the lightat different incident angles when a captured image is not good.Furthermore, a technique/technology that takes into account thereflection of light by eyeglasses or spectacles or the like when theiris image is captured, has also been proposed (e.g., see PatentLiteratures 2 to 4).

CITATION LIST Patent Literature Patent Literature 1: JPH10-005195APatent Literature 2: JP2001-167284A Patent Literature 3: JP2008-276328APatent Literature 4: JP2015-112151A SUMMARY Technical Problem

When the target person is wearing eyeglasses, an eyeglass lens mayreflect illumination light, which may lead to fail to obtain irisfeatures in a reflective area. Each cited document mentioned above hasinsufficient discussion on such problems, and there is room forimprovement.

It is an example object to provide an imaging system, an imaging method,and a computer program that are configured to solve the problemsdescribed above.

Solution to Problem

An imaging system according to an example aspect of this disclosureincludes: an imaging unit that captures an image of an eye area of atarget person by using an image sensor that allows imaging withoutsaturating observed light; an acquisition unit that obtains, from theimage, a first information about a first area that does not includereflection of light by an eyeglass lens of the target person, and asecond information about a second area that includes the reflection ofthe light; and a correction unit that corrects the second information soas to reduce an influence of the reflection, on the basis of the firstinformation.

An imaging method according to an example aspect of this disclosureincludes: capturing an image of an eye area of a target person by usingan image sensor that allows imaging without saturating observed light;obtaining, from the image, a first information about a first area thatdoes not include reflection of light by an eyeglass lens of the targetperson, and a second information about a second area that includes thereflection of the light; and correcting the second information so as toreduce an influence of the reflection, on the basis of the firstinformation.

A computer program according to an example aspect of this disclosureoperates a computer: to capture an image of an eye area of a targetperson by using an image sensor that allows imaging without saturatingobserved light; to obtain, from the image, a first information about afirst area that does not include reflection of light by an eyeglass lensof the target person, and a second information about a second area thatincludes the reflection of the light; and to correct the secondinformation so as to reduce an influence of the reflection, on the basisof the first information.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating a hardware configuration of animaging system according to a first example embodiment.

FIG. 2 is a block diagram illustrating a functional configuration of theimaging system according to the first example embodiment.

FIG. 3 is a block diagram illustrating a functional configuration of animaging system according to a modified example of the first exampleembodiment.

FIG. 4 is a diagram illustrating an imaging example when lightreflection occurs on an eyeglass lens.

FIG. 5 is a conceptual diagram illustrating a path of light reflected byan iris of a target person and a path of light reflected by the eyeglasslens.

FIG. 6 is a flowchart illustrating a flow of operation of the imagingsystem according to the first example embodiment.

FIG. 7 is a block diagram illustrating a functional configuration of animaging system according to a second example embodiment.

FIG. 8 is a flowchart illustrating a flow of operation of the imagingsystem according to the second example embodiment.

FIG. 9 is a flowchart illustrating a flow of operation of an imagingsystem according to a third example embodiment.

FIG. 10 is a diagram illustrating an example of a plurality of imagescaptured in different brightness ranges.

FIG. 11 is a graph illustrating an example of amount of light observedin a first area and a second area.

FIG. 12 is a conceptual diagram illustrating a method of calculating anaverage value of pixel values of the first area and an average value ofpixel values of the second area.

FIG. 13 is a graph illustrating a difference between the average valueof the pixel values of the first area and the average value of the pixelvalues of the second area.

FIG. 14 is a graph illustrating an example of a pixel value aftercorrection by using the average value of the pixel values.

FIG. 15 is a block diagram illustrating a functional configuration of animaging system according to a fifth example embodiment.

FIG. 16A and FIG. 16B are Version 1 of a diagram illustrating a displayexample in the imaging system according to the fifth example embodiment.

FIG. 17A and FIG. 17B are Version 2 of a diagram illustrating a displayexample in the imaging system according to the fifth example embodiment.

FIG. 18A and FIG. 18B are Version 3 of a diagram illustrating a displayexample in the imaging system according to the fifth example embodiment.

FIG. 19 is a block diagram illustrating a functional configuration of animaging system according to a sixth example embodiment.

FIG. 20 is a flowchart illustrating a flow of operation of the imagingsystem according to the sixth example embodiment.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Hereinafter, an imaging system, an imaging method, and a computerprogram according to example embodiments will be described withreference to the drawings.

First Example Embodiment

An imaging system according to a first example embodiment will bedescribed with reference to FIG. 1 to FIG. 6 .

Hardware Configuration

First, with reference to FIG. 1 , a hardware configuration of theimaging system according to the first example embodiment will bedescribed. FIG. 1 is a block diagram illustrating the hardwareconfiguration of the imaging system according to the first exampleembodiment.

As illustrated in FIG. 1 , an imaging system 10 according to the firstexample embodiment includes a processor 11, a RAM (Random Access Memory)12, a ROM (Read Only Memory) 13, and a storage apparatus 14. The imagingsystem 10 may also include an input apparatus 15 and an output apparatus16. The processor 11, the RAM 12, the ROM 13, the storage apparatus 14,the input apparatus 15, and the output apparatus 16 are connectedthrough a data bus 17.

The processor 11 reads a computer program. For example, the processor 11is configured to read a computer program stored in at least one of theRAM 12, the ROM 13 and the storage apparatus 14. Alternatively, theprocessor 11 may read a computer program stored by a computer readablerecording medium by using a not-illustrated recording medium readingapparatus. The processor 11 may obtain (i.e., read) a computer programfrom a not-illustrated apparatus that is located outside the imagingsystem 10 through a network interface. The processor 11 controls the RAM12, the storage apparatus 14, the input apparatus 15, and the outputapparatus 16 by executing the read computer program. Especially in thefirst example embodiment, when the processor 11 executes the readcomputer program, a functional block for processing an iris image of atarget person is realized or implemented in the processor 11. As theprocessor 11, one of a CPU (Central Processing Unit), a GPU (GraphicsProcessing Unit), a FPGA (field-programmable gate array), a DSP (digitalsignal processor), and an ASIC (application specific integrated circuit)may be used, or a plurality of them may be used in parallel.

The RAM 12 temporarily stores the computer program to be executed by theprocessor 11. The RAM 12 temporarily stores the data that is temporarilyused by the processor 11 when the processor 11 executes the computerprogram. The RAM 12 may be, for example, a D-RAM (Dynamic RAM).

The ROM 13 stores the computer program to be executed by the processor11. The ROM 13 may otherwise store fixed data. The ROM 13 may be, forexample, a P-ROM (Programmable ROM).

The storage apparatus 14 stores the data that is stored for a long termby the imaging system 10. The storage apparatus 14 may operate as atemporary storage apparatus of the processor 11. The storage apparatus14 may include, for example, at least one of a hard disk apparatus, amagneto-optical disk apparatus, an SSD (Solid State Drive), and a diskarray apparatus.

The input apparatus 15 is an apparatus that receives an inputinstruction from a user of the imaging system 10. The input apparatus 15may include, for example, at least one of a keyboard, a mouse, and atouch panel.

The output apparatus 16 is an apparatus that outputs information aboutthe imaging system 10 to the outside. For example, the output apparatus16 may be a display apparatus (e.g., a display) that is configured todisplay the information about the imaging system 10.

Functional Configuration

Next, with reference to FIG. 2 , a functional configuration of theimaging system 10 according to the first example embodiment will bedescribed. FIG. 2 is a block diagram illustrating the functionalconfiguration of the imaging system according to the first exampleembodiment.

As illustrated in FIG. 2 , the imaging system 10 according to the firstexample embodiment is configured to capture an image of a target personP (especially, an image of the periphery of an eye including an iris).The imaging system 10 may be configured, for example, as a part of asystem that performs iris authentication of the target person P. Theimaging system 10 includes an imaging unit 110, an irradiation unit 120,and a calculation unit 130.

The imaging unit 110 is configured, for example, as a camera disposed ata position at which the target person P can be captured. The imagingunit 110 has resolution that allows features of the iris (hereinafterreferred to “iris features” as appropriate) of the target person P. Theimaging unit 110 includes an image sensor having a dynamic range thatallows imaging without saturating reflected light from the vicinity ofan eye area. More specifically, the imaging unit 110 includes an imagesensor having a dynamic range in which a pixel value is not saturated inboth an area that does not include reflection of light (hereinafterreferred to as a “first area” as appropriate) even when light reflectionoccurs on a lens surface of eyeglasses that the target person P iswearing, and an area that includes the reflection of light (hereinafterreferred to as a “second area” as appropriate). As an example of such animage sensor, an image sensor illustrated in Non-Patent Literature 1 canbe used.

Non-Patent Literature 1: M. Murata et al., “A High Near-InfraredSensitivity Over 70-dB SNR CMOS Image Sensor With Lateral OverflowIntegration Trench Capacitor,” IEEE TRANSACTIONS ON ELECTRON DEVICES,pp. 1-7, 2020.

When imaging is performed by the imaging unit 110, exposure, shutterspeed, gain, and the like are adjusted as appropriate such that the irisfeatures of the target person P are effectively captured as an image.The image of the eye area of the target person P captured by the imagingunit 110 is configured to be outputted to the calculation unit 130.

The irradiation unit 120 applies illumination light to the target personP when the imaging unit 110 captures the image of the target person P.The irradiation timing of the irradiation unit 120 may be synchronizedwith the imaging timing of the imaging unit 110. The number of theirradiation unit 120 is not limited to one, and a plurality ofirradiation units 120 may be provided. In this case, the illuminationlight may be applied by the plurality of irradiation units 120simultaneously, or the illumination light may be applied from a part ofthe irradiation units 120 depending on the situation. When the pluralityof irradiation units 120 are provided, they may be arrangedtwo-dimensionally (i.e., on the same plane) or may be arrangedthree-dimensionally.

The calculation unit 130 is configured to perform various processes onthe image captured by the imaging unit 110. The calculation unit 130 maybe configured, for example, as a part of the processor 11 in FIG. 1 .The calculation unit 130 includes an acquisition unit 131 and acorrection unit 132 as processing blocks for realizing the function.

The acquisition unit 131 is configured to obtain information about theiris from the image captured by the imaging unit 110. The acquisitionunit 131 is especially configured to obtain a first information aboutthe first area (i.e., the area that does not include the reflection oflight by an eyeglass lens) and a second information about the secondarea (i.e., the area that includes the reflection of light by theeyeglass lens). The first information and the second information areobtained, for example, as the pixel value. When the light reflectiondoes not occur on the eyeglass lens, the acquisition unit 131 may beconfigured to obtain only the first information. The first informationand the second information obtained by the acquisition unit 131 areconfigured to be outputted to the correction unit 132.

The correction unit 132 is configured to correct the second informationon the basis of the first information. More specifically, the correctionunit 132 corrects the second information such that an influence of thelight reflection on the eyeglass lens included in the second informationis reduced (preferably to be zero).

Modified Example

Next, with reference to FIG. 3 , the imaging system 10 according to amodified example of the first example embodiment will be described. FIG.3 is a block diagram illustrating a functional configuration of theimaging system according to the modified example of the first exampleembodiment. In FIG. 3 , the same components as those illustrated in FIG.2 carry the same reference numerals.

As illustrated in FIG. 3 , the imaging system 10 according to themodified example includes the imaging unit 110 and the calculation unit130. That is, the imaging system 10 may not necessarily include theirradiation unit 120. In this case, the target person P may beilluminated with light from outside lighting of the system (e.g.,fluorescent lamps, etc.), or with natural light or the like.

Influence of Light Reflection by Eyeglass lens

Next, the influence of the light reflection that occurs on the eyeglasslens on the image will be described with reference to FIG. 4 . FIG. 4 isa diagram illustrating an imaging example when the light reflectionoccurs on the eyeglass lens.

As illustrated in FIG. 4 , when the target person P is wearingeyeglasses, the illumination light applied from the irradiation unit 120may be reflected by the eyeglass lens, which may influence the imagecaptured by the imaging unit 110. Specifically, the second area, whichis influenced by the light reflection, may overlap an area of the irisof the target person P, and this may make it hardly possible to properlyobtain the iris features. In particular, when the dynamic range of theimage sensor is narrow (e.g., about 50 dB), the pixel value of thesecond area influenced by the reflection on the eyeglass lens may besaturated, and the iris features may not be obtained at all. To avoidsuch a situation, the imaging system 10 according to the first exampleembodiment includes the image sensor having the dynamic range thatallows the imaging without saturating reflected light, as alreadydescribed.

Path of Reflected Light

Next, a path of the illumination light, which is applied from theirradiation unit 120, up to the imaging unit 110 will be specificallydescribed with reference to FIG. 5 . FIG. 5 is a conceptual diagramillustrating the path of the light reflected by the iris of the targetperson and the light reflected by the eyeglass lens.

As illustrated in FIG. 5 , the illumination light applied from theirradiation unit 120 is divided into a component of reflected light Areflected by a front or rear surface of an eyeglass lens 200 toward theimaging unit 110 and a component of reflected light B reflected by aniris E of the target person P toward the imaging unit 110. Here,reflected light from the first area includes the reflected light B. Onthe other hand, reflected light from the second area includes both thereflected light A and the reflected light B. Therefore, if a correctionof separating those derived from the component of the reflected light Acan be performed on the second information about the second area, it ispossible to reduce the influence of the reflection on the eyeglass lens200.

Flow of Operation

Next, with reference to FIG. 6 , a flow of operation of the imagingsystem 10 according to the first example embodiment will be described.FIG. 6 is a flowchart illustrating the flow of the operation of theimaging system according to the first example embodiment.

As illustrated in FIG. 6 , in operation of the imaging system 10according to the first example embodiment, first, the imaging unit 110captures the image of the eye area of the target person P (step S101).

Subsequently, the acquisition unit 131 obtains the first information andthe second information, and determines whether or not there is anysecond area (step S102). In other words, the acquisition unit 131determines whether or not there is an area that includes the reflectionof light by the eyeglass lens 200. Whether or not there is any secondarea can be determined, for example, by whether or not there is a partwhere amount of light is locally increased.

When there is no second area (the step S102: NO), there is only thefirst area, and there is no need to consider the influence of lightreflection. Therefore, in this case, a series of processing steps isended.

On the other hand, when there is the second area (the step S102: YES),it is hard to obtain the iris features in the second area as it is.Therefore, in this case, the correction unit 132 corrects the secondinformation on the basis of the first information (step S104). Aspecific correction method here will be described in detail in a fourthexample embodiment later.

Technical Effect

Next, a technical effect obtained by the imaging system 10 according tothe first example embodiment will be described.

As described in FIG. 1 to FIG. 6 , in the imaging system 10 according tothe first example embodiment, the second information that indicates thereflection of light by the eyeglass lens 200 is corrected by thecorrection unit 132. Consequently, it is possible to reduce theinfluence of the reflection on the eyeglass lens 200, and it is alsopossible to obtain the iris features of the target person P for thesecond area.

Second Example Embodiment

The imaging system 10 according to a second example embodiment will bedescribed with reference to FIG. 7 and FIG. 8 . The second exampleembodiment is partially different from the first example embodimentdescribed above only in configuration and operation, and may be the sameas the first example embodiment, for example, in hardware configuration(see FIG. 1 ). Therefore, in the following, a description of the partsthat overlap the first example embodiment will be omitted asappropriate.

As illustrated in FIG. 7 , the imaging system 10 according to the secondexample embodiment includes the imaging unit 110, the irradiation unit120, and the calculation unit 130. In particular, the calculation unit130 according to the second example embodiment includes the acquisitionunit 131, the correction unit 132, and a generation unit 133. That is,the calculation unit 130 according to the second example embodimentfurther includes the generation unit 133 in addition to theconfiguration in the first example embodiment.

The generation unit 133 is configured to generate the iris imageincluding the iris features of the target person P from the firstinformation obtained by acquisition unit 131 and from the secondinformation corrected by the correction unit 132. For example, thegeneration unit 133 generates the iris image of the target person P byusing an iris information included in the first information (i.e., theiris information obtained originally without being influenced by thelight reflection) and an iris information included in the correctedsecond information (i.e., the iris information obtained because theinfluence of the light reflection is reduced by the correction). Thegeneration unit 133 may have a function of outputting the generated irisimage.

Flow of Operation

Next, with reference to FIG. 8 , a flow of operation of the imagingsystem 10 according to the first example embodiment will be described.FIG. 8 is a flowchart illustrating the flow of the operation of theimaging system according to the second example embodiment. In FIG. 8 ,the same steps as those illustrated in FIG. 6 carry the same referencenumerals.

As illustrated in FIG. 8 , in operation of the imaging system 10according to the second example embodiment, first, the imaging unit 110captures the image of the eye area of the target person P (the stepS101). Subsequently, the acquisition unit 131 obtains the firstinformation and the second information, and determines whether or notthere is any second area (the step S102).

When there is no second area (the step S102: NO), there is only thefirst area, and there is no need to consider the influence of lightreflection. Therefore, in this case, the generation unit 133 generatesthe iris image from the first information about the first area (stepS103).

On the other hand, when there is the second area (the step S102: YES),it is hard to obtain the iris features in the second area as it is.Therefore, in this case, the correction unit 132 corrects the secondinformation on the basis of the first information (the step S104). Then,the generation unit 133 generates the iris image from the firstinformation and the corrected second information (step S105).

Technical Effect

Next, a technical effect obtained by the imaging system 10 according tothe second example embodiment will be described.

As described in FIG. 7 and FIG. 8 , in the imaging system 10 accordingto the second example embodiment, the iris image is generated from thefirst information and the corrected second information. Thus, even whenthe light reflection by the eyeglass lens 200 occurs, it is possible toproperly generate the iris image. Such a technical effect issignificantly demonstrated, for example, when iris authentication thatrequires precise iris features is performed. For example, thiseliminates a need for the target person P to remove eyeglasses, orreduces a risk of re-imaging, which greatly improves convenience whenthe iris image is captured.

Third Example Embodiment

The imaging system 10 according to a third example embodiment will bedescribed with reference to FIG. 9 . The third example embodiment ispartially different from the first and second example embodimentsdescribed above only in operation, and may be the same as the first andsecond example embodiments in configuration (see FIG. 1 , FIG. 2 , FIG.3 , and FIG. 7 ). Therefore, in the following, a description of theparts that overlap the first and second example embodiments will beomitted as appropriate.

Flow of Operation

First, with reference to FIG. 9 , a flow of operation of the imagingsystem 10 according to the third example embodiment will be described.FIG. 9 is a flowchart illustrating the flow of the operation of theimaging system according to the third example embodiment. In FIG. 9 ,the same steps as those illustrated in FIG. 6 and FIG. 8 carry the samereference numerals.

As illustrated in FIG. 9 , in operation of the imaging system 10according to the third example embodiment, first, the imaging unit 110captures a plurality of images of the eye area of the target person P intwo or more different brightness ranges (step S201). For example, whenimages are captured in two brightness ranges, the imaging unit 110 maycapture one image in a relatively low brightness range and may captureone image in a relatively high brightness range.

Subsequently, the acquisition unit 131 obtains the first information andthe second information from one image, and determines whether or notthere is any second area (the step S102). The one image is preferably animage captured in a brightness range from which the iris features can beproperly obtained from the first information (e.g., an image with thelowest brightness range).

When there is no second area (the step S102: NO), there is only thefirst area, and thus, the generation unit 133 generates the iris imagefrom the first information obtained from the one image (the step S103).

On the other hand, when there is the second area (the step S102: YES),the acquisition unit 131 obtains the second information from anotherimage (i.e., an image with a brightness range that is different fromthat of the one image) (step S202). This another image is preferably animage that allows the iris features of the second area to be obtained tosome extent (e.g., an image with a brightness range that is higher thanthat of the one image).

Then, the correction unit 132 corrects the second information on thebasis of the first information (the step S104). Then, the generationunit 133 generates the iris image from the first information and thecorrected second information (the step S105).

Technical Effect

Next, a technical effect obtained by the imaging system 10 according tothe third example embodiment will be described.

As described in FIG. 9 , in the imaging system 10 according to the thirdexample embodiment, the iris image of the target person P is generatedby using a plurality of images captured in two or more brightnessranges. Here, if the brightness range is fixed, the iris features ofboth the first area and the second area may not be obtained from theimage captured in the fixed brightness range. In the third exampleembodiment, however, since a plurality of images captured in two or morebrightness ranges are used, it is possible to separately obtain thefirst information and second information from the respective images.Thus, it is possible to generate the iris image of the target person P,more properly.

Modified Example

Here, with reference to FIG. 10 , the imaging system 10 according to amodified example of the third example embodiment will be described. FIG.10 is a diagram illustrating an example of a plurality of imagescaptured in different brightness ranges.

As illustrated in FIG. 10 , in the imaging system 10 according to themodified example, the imaging unit 110 captures the images of the targetperson P in five different brightness ranges. In this example, the irisfeatures about the first area can be obtained from an image of lowbrightness with the lowest brightness range, while the iris featuresabout the second area cannot be obtained. Specifically, in the image oflow brightness, the pixel value of the second area is saturated (wheneach image has a bit depth of 8 bits, the saturated pixel value is 255).

In such a case, the acquisition unit 131 obtains the second informationabout the second area from a non-saturated image in which the pixelvalue of the second area is not saturated. Specifically, the secondinformation is obtained from an image of maximum brightness with thehighest brightness range. In the image of maximum brightness, as can beseen from FIG. 10 , the pixel value is saturated in a peripheral partother than the second area, but the pixel value is not saturated in thesecond area, and the iris features can be obtained as the secondinformation.

Thus, even when the pixel value of the second area is saturated in theimage of low brightness, it is possible to properly generate the irisimage by obtaining the second information from the image in which thepixel value is not saturated in the second area. The above-describedexample describes that the second information is obtained from the imageof maximum brightness; however, when the pixel value of the second areais not saturated even in an image group of middle to high brightness,the second information may be obtained therefrom.

Fourth Example Embodiment

The imaging system 10 according to a fourth example embodiment will bedescribed with reference to FIG. 11 to FIG. 14 . The fourth exampleembodiment is an example embodiment for describing a specific method ofcorrecting the second information in the first to third exampleembodiments described above (i.e., a specific operation example of thecorrection unit 132), and may be the same as the first exampleembodiment (see FIG. 1 , FIG. 2 and FIG. 5 ), the second exampleembodiment (see FIG. 8 ), or the third example embodiment (see FIG. 9 )in configuration and flow of operation. Therefore, in the following, adescription of the parts that overlap those already described will beomitted as appropriate.

Amount of Light in First Area and Second Area

First, with reference to FIG. 11 , the amount of light of the reflectedlight in the first area and second area will be described. FIG. 11 is agraph illustrating an example of the amount of light observed in thefirst area and the second area. This graph is a plot of values obtainedby scanning a thick line part that crosses the first area and the secondarea in FIG. 11 , in a lateral direction (i.e., an X-axis direction).

As illustrated in FIG. 11 , since observed light has a relatively smallamount of light in the first area in which the light reflection does notoccur on the eyeglass lens 200, the pixel value is reduced. On the otherhand, since the observed light has an increased amount of light in thesecond area in which the light reflection occurs on the eyeglass lens200, the pixel value is increased.

Here, for the reflected light reflected by the iris (i.e., the reflectedlight B in FIG. 4 ), the amount of light varies due to visual featuresof the iris. On the other hand, for the reflected light reflected by theeyeglass lens 200 (i.e., the reflected light A in FIG. 4 ), the amountof light is substantially uniform because there are no visual features,such as a pattern, in the eyeglass lens 200. By using this difference inthe features, it is possible to perform the correction of separating thecomponent of the reflected light A and the component of the reflectedlight B (in other words, a correction of removing only the component ofthe reflected light A).

Correction of Pixel Value

Next, a method of correcting the pixel value will be described withreference to FIG. 12 to FIG. 14 . FIG. 12 is a conceptual diagramillustrating a method of calculating an average value of pixel values ofthe first area and an average value of pixel values of the second area.FIG. 13 is a graph illustrating a difference between the average valueof the pixel values of the first area and the average value of the pixelvalues of the second area. FIG. 14 is a graph illustrating an example ofa pixel value after correction by using the average value of the pixelvalues.

In FIG. 12 , an area surrounded by a solid line indicates the pixelvalue of the iris area (i.e., the pixel value of the first area). Anarea surrounded by a dotted line indicates the pixel value of the areainfluenced by the light reflection of the eyeglass lenses 200 (i.e., thepixel value of the second area). The first area and the second area canbe easily distinguished by using such a characteristic that they havesignificantly different pixel values from each other.

In the imaging system 10 according to the fourth example embodiment, thecorrection unit 132 calculates an average value O(bar)i of the pixelvalues of the first area, wherein O(bar) means a letter O with macron.The correction unit 132 also calculates an average value O(bar)g of thepixel values of the second area. Here, the average value O(bar)iindicates the average value of the light reflected by the iris (i.e.,the reflected light B in FIG. 4 ). The average value O(bar)g indicatesthe average value of the sum of the light reflected by the iris and thelight reflected by the eyeglass lens 200 (i.e., the sum of the reflectedlight A and the reflected light B in FIG. 4 ). Therefore, the averagevalue O(bar)a of the reflected light A can be calculated by using thefollowing equation (1).

[Equation 1]

Ōa=Ōg−Ōi  (1)

Furthermore, by using a coefficient α considering a predeterminedmargin, calculation may be performed as in the following equation (2).

[Equation 2]

Ōa=Ōg−Ōi+α  (2)

Here, α may be a value that is statistically determined by experiments,or may be a value that can be arbitrarily set by a user. When thegenerated iris image is displayable as in a fifth example embodimentdescribed later, the value of α may be adjusted on a display screen toupdate the display of the iris image at each time of the adjustment.

As illustrated in FIG. 13 , the average value O(bar)a of the reflectedlight A reflected by the eyeglass lens 200 can be represented on a graphas a length between a straight line indicating the average value O(bar)iand a straight line indicating the average value O(bar)g. When theaverage value O(bar)a is obtained, not only one line on the imageillustrated in FIG. 12 , but also a plurality of lines may be used toobtain the average value of the pixel values of each area.

The correction unit 132 calculates a pixel value Oi(x,y) of the firstarea from a pixel value Og(x,y) at a coordinate position (x,y) on theimage of the second area (see Equation (3) below).

[Equation 3]

Oi(x,y)=Og(x,y)−Ōa  (3)

By following the above procedure, as illustrated in FIG. 14 , the pixelvalue Oi(x,y) obtained by removing the influence of the reflected lighton the eyeglass lens 200 from the pixel value of the second area iscalculated. By obtaining the pixel value Oi(x,y) for all the pixelsinfluenced by the reflected light from the eyeglass lens 200, it ispossible to generate the iris image that captures the visual features ofthe eyes of the target person P.

Fifth Example Embodiment

The imaging system 10 according to a fifth example embodiment will bedescribed with reference to FIG. 15 to FIG. 18B. The fifth exampleembodiment is partially different from the first to fourth exampleembodiments described above only in configuration, and may be the sameas the first example embodiment (see FIG. 1 , FIG. 2 and FIG. 5 ), thesecond example embodiment (see FIG. 7 and FIG. 8 ), or the third exampleembodiment (see FIG. 9 ) in hardware configuration and flow of operationor the like. Therefore, in the following, a description of the partsthat overlap those already described will be omitted as appropriate.

Functional Configuration

First, with reference to FIG. 15 , a functional configuration of theimaging system 10 according to a fifth example embodiment will bedescribed. FIG. 15 is a block diagram illustrating the functionalconfiguration of the imaging system according to the fifth exampleembodiment. In FIG. 12 , the same components as those illustrated inFIG. 2 carry the same reference numerals.

As illustrated in FIG. 15 , the imaging system 10 according to the fifthexample embodiment includes the imaging unit 110, the irradiation unit120, the calculation unit 130, and a display unit 140. That is, theimaging system 10 according to the fifth example embodiment furtherincludes the display unit 140 in addition to the configuration in thefirst example embodiment (see FIG. 2 ).

The display unit 140 is configured as a monitor having a display, forexample. The display unit 140 may be configured as a part of the outputapparatus 16 illustrated in FIG. 1 . The display unit 140 is configuredto display at least one of the iris image generated by the generationunit 133 and a registered image for an authentication process that usesthe iris image.

Display Example

Next, a display example of the imaging system 10 according to the fifthexample embodiment will be described with reference to FIG. 16A to FIG.18B. A first display example to a third display example described belowmay be combined to use as appropriate.

First Display Example

With reference to FIG. 16A and FIG. 16B, a first display example will bedescribed. FIG. 16A and FIG. 16B are Version 1 of a diagram illustratingthe display example in the imaging system according to the fifth exampleembodiment.

As illustrated in FIG. 16A, the display unit 140 may display theregistered image and the iris image side by side. At this time, thedisplay unit 140 may perform display in such a manner thatdisplay/non-display of the registered image and the iris image isswitchable. Specifically, a button for switching between display andnon-display may be displayed below each image. In this case, when abutton for hiding the registered image is pressed, the registered imageis hidden and only the iris image is displayed, as illustrated in FIG.16B. When only one of the images is displayed, an image to be displayedmay be enlarged and displayed in the center.

Second Display Example

With reference to FIG. 17A and FIG. 17B, a second display example willbe described. FIG. 17A and FIG. 17B are Version 2 of a diagramillustrating the display example in the imaging system according to thefifth example embodiment.

As illustrated in FIG. 17A, the display unit 140 may perform display insuch a manner that correction/no correction of the iris image isswitchable. Specifically, a button for switching between correction andno correction may be displayed below the iris image. In this case, whena button for no correction is pressed, the iris image is displayed in astate before correction (i.e., a state of the imaging in which thecorrection is not performed by the correction unit 132), as illustratedin FIG. 17B. In this way, it is possible to know what part of the irisimage is corrected and how it is corrected. The iris image beforecorrection and the iris image after correction may be displayedsimultaneously.

Third Display Example

With reference to FIG. 18A and FIG. 18B, a third display example will bedescribed. FIG. 18A and FIG. 18B are Version 3 of a diagram illustratingthe display example in the imaging system according to the fifth exampleembodiment.

As illustrated in FIG. 18A, the display unit 140 may perform display insuch a manner that highlighting ON/OFF of a corrected part (in otherwords, a part corresponding to the second area) is switchable.Specifically, a button for switching between highlighting ON andhighlighting OFF may be displayed below the registered image and theiris image. In this case, when the button is pressed such that thehighlighting is ON for both the registered image and the iris image, thepart corresponding to the second area of each of the registered imageand the iris image is surrounded by a frame and displayed, asillustrated in FIG. 18B. In this way, it is possible to know which partof the iris image is corrected. The display of surrounding the part bythe frame is an example of the highlighting, and the highlighting may beperformed in another aspect (e.g., changing color and density, orflashing, etc.).

Sixth Example Embodiment

The imaging system 10 according to a sixth example embodiment will bedescribed with reference to FIG. 19 and FIG. 20 . The sixth exampleembodiment is partially different from the first to fifth exampleembodiments described above only in configuration and operation, and maybe the same as the first example embodiment, for example, in hardwareconfiguration (see FIG. 1 ). Therefore, in the following, a descriptionof the parts that overlap those already described will be omitted asappropriate.

As illustrated in FIG. 19 , the imaging system 10 according to the sixthexample embodiment includes the imaging unit 110, and the calculationunit 130. In particular, the calculation unit 130 according to the sixthexample embodiment includes the acquisition unit 131 and an eyeglassdetection unit 134. That is, the calculation unit 130 according to thesixth example embodiment includes the eyeglass detection unit 134 inplace of the correction unit 132 in each of the example embodimentsdescribed above.

The eyeglass detection unit 134 is configured to detect that the targetperson P is wearing eyeglasses on the basis of the first information andthe second information obtained by the acquisition unit 131. Forexample, when both the first information and the second information areobtained by the acquisition unit 131, the eyeglass detection unit 134detects that the target person P is wearing eyeglasses. On the otherhand, when only the first information is obtained by the acquisitionunit 131, the eyeglass detection unit 134 does not detect the targetperson P is wearing eyeglasses.

Flow of Operation

Next, with reference to FIG. 20 , a flow of operation of the imagingsystem 10 according to the sixth example embodiment will be described.FIG. 20 is a flowchart illustrating the flow of the operation of theimaging system according to the sixth example embodiment.

As illustrated in FIG. 8 , in operation of the imaging system 10according to the sixth example embodiment, first, the imaging unit 110captures the image of the eye area of the target person P (step S501).Then, the acquisition unit 131 obtains the first information and thesecond information (step S502).

Subsequently, the eyeglass detection unit 134 performs an eyeglassdetection process on the basis of an acquisition result of theacquisition unit 131 (i.e., the first information and the secondinformation) (step S503). When detecting that the target person P iswearing eyeglasses, the eyeglass detection unit 134 may output theinformation to the display or the like.

Technical Effect

Next, a technical effect obtained by the imaging system 10 according tothe sixth example embodiment will be described.

As described in FIG. 19 and FIG. 20 , in the imaging system 10 accordingto the sixth example embodiment, it is detected that the target person Pis wearing eyeglasses on the basis of the acquisition result of theacquisition unit 131 (specifically, the first information that does notindicate the reflection of light by the eyeglasses, and the secondinformation that indicates the reflection of light by the eyeglasses).Therefore, it is possible to properly determine whether or not thetarget person P is wearing eyeglasses, from the image obtained byimaging the target person P.

Supplementary Notes

The example embodiments described above may be further described as, butnot limited to, the following Supplementary Notes.

Supplementary Note 1

An imaging system described in Supplementary Note 1 is an imaging systemincluding: an imaging unit that captures an image of an eye area of atarget person by using an image sensor that allows imaging withoutsaturating observed light; an acquisition unit that obtains, from theimage, a first information about a first area that does not includereflection of light by an eyeglass lens of the target person, and asecond information about a second area that includes the reflection ofthe light; and a correction unit that corrects the second information soas to reduce an influence of the reflection, on the basis of the firstinformation.

Supplementary Note 2

An imaging system described in Supplementary Note 2 is the imagingsystem described in Supplementary Note 1, further including anirradiation unit that applies illumination light to the eye area.

Supplementary Note 3

An imaging system described in Supplementary Note 3 is the imagingsystem described in Supplementary Note 1 or 2, further including ageneration unit that generates an iris image including iris features ofthe target person from the first information and from the correctedsecond information.

Supplementary Note 4

An imaging system described in Supplementary Note 4 is the imagingsystem described in any one of Supplementary Notes 1 to 3, wherein, theimaging unit captures a plurality of images in two or more differentbrightness ranges, and the acquisition unit obtains each of the firstinformation and the second information from the images captured indifferent brightness ranges.

Supplementary Note 5

An imaging system described in Supplementary Note 5 is the imagingsystem described in Supplementary Note 4, wherein the acquisition unitselects a non-saturated image in which a pixel value of the second areais not saturated from the images captured in different brightnessranges, and obtains the second information from the non-saturated image.

Supplementary Note 6

An imaging system described in Supplementary Note 6 is the imagingsystem described in any one of Supplementary Notes 1 to 5, wherein thecorrection unit corrects the second information by subtracting a valuebased on an average value of pixel values of the first area from anaverage value of pixel values of the second area.

Supplementary Note 7

An imaging system described in Supplementary Note 7 is the imagingsystem described in any one of Supplementary Notes 1 to 6, furtherincluding a display unit that displays at least one of an iris image anda registered image used for an authentication process of the iris image.

Supplementary Note 8

An imaging system described in Supplementary Note 8 is the imagingsystem described in Supplementary Note 7, wherein the display unitdisplays the iris image and the image captured by the imaging unit,simultaneously or alternatively.

Supplementary Note 9

An imaging system described in Supplementary Note 9 is the imagingsystem described in Supplementary Note 7 or 8, wherein the display unithighlights at least one of a part corresponding to the second area ofthe iris image and a part corresponding to the second area of theregistered image.

Supplementary Note 10

An imaging system described in Supplementary Note 10 is the imagingsystem described in Supplementary Note 9, wherein the display unit isconfigured to switch between presence and absence of highlighting.

Supplementary Note 11

An imaging method described in Supplementary Note 11 is an imagingmethod including: capturing an image of an eye area of a target personby using an image sensor that allows imaging without saturating observedlight; obtaining, from the image, a first information about a first areathat does not include reflection of light by an eyeglass lens of thetarget person, and a second information about a second area thatincludes the reflection of the light; and correcting the secondinformation so as to reduce an influence of the reflection, on the basisof the first information.

Supplementary Note 12

A computer program described in Supplementary Note 12 is a computerprogram that operates a computer: to capture an image of an eye area ofa target person by using an image sensor that allows imaging withoutsaturating observed light; to obtain, from the image, a firstinformation about a first area that does not include reflection of lightby an eyeglass lens of the target person, and a second information abouta second area that includes the reflection of the light; and to correctthe second information so as to reduce an influence of the reflection,on the basis of the first information.

Supplementary Note 13

An imaging system described in Supplementary Note 13 is an imagingsystem including: an imaging unit that captures an image of an eye areaof a target person by using an image sensor that allows imaging withoutsaturating observed light; an acquisition unit that obtains, from theimage, a first information about a first area that does not includereflection of light by an eyeglass lens of the target person, and asecond information about a second area that includes the reflection ofthe light; and a detection unit that detects eyeglasses of the targetperson on the basis of an acquisition result of the acquisition unit.

Supplementary Note 14

An imaging method described in Supplementary Note 14 is an imagingmethod including: capturing an image of an eye area of a target personby using an image sensor that allows imaging without saturating observedlight; obtaining, from the image, a first information about a first areathat does not include reflection of light by an eyeglass lens of thetarget person, and a second information about a second area thatincludes the reflection of the light; and detecting eyeglasses of thetarget person on the basis of an acquisition result of the acquisitionunit.

Supplementary Note 15

A computer program described in Supplementary Note 15 is a computerprogram that operates a computer: to capture an image of an eye area ofa target person by using an image sensor that allows imaging withoutsaturating observed light; to obtain, from the image, a firstinformation about a first area that does not include reflection of lightby an eyeglass lens of the target person, and a second information abouta second area that includes the reflection of the light; and to detecteyeglasses of the target person on the basis of an acquisition result ofthe acquisition unit.

Supplementary Note 16

A recording medium described in Supplementary Note 16 is a recordingmedium on which the computer program described in Supplementary Note 12or 15 is recorded.

This disclosure is not limited to the examples described above and isallowed to be changed, if desired, without departing from the essence orspirit of the invention which can be read from the claims and the entirespecification. An imaging system, an imaging method, and a computerprogram with such modifications are also intended to be within thetechnical scope of this disclosure.

DESCRIPTION OF REFERENCE CODES

-   10 Imaging system-   11 Processor-   110 Imaging unit-   111 Lens-   112 Image sensor-   120 Irradiated unit-   130 Calculation unit-   131 Acquisition unit-   132 Correction unit-   133 Generation unit-   134 Eyeglass detection unit-   140 Display unit-   200 Eyeglass lens-   P Target person

What is claimed is:
 1. An imaging system comprising: a camera that captures an image of an eye area of a target person by using an image sensor that allows imaging without saturating observed light; at least one memory that is configured to store instructions; and at least one first processor that is configured to execute the instructions to obtain, from the image, a first information about a first area that does not include reflection of light by an eyeglass lens of the target person, and a second information about a second area that includes the reflection of the light; and correct the second information so as to reduce an influence of the reflection, on the basis of the first information.
 2. The imaging system according to claim 1, further comprising a second processor that is configured to execute instructions to apply illumination light to the eye area.
 3. The imaging system according to claim 1, further comprising a third processor that is configured to execute instructions to generate an iris image including iris features of the target person from the first information and from the corrected second information.
 4. The imaging system according to claim 1, wherein, the camera captures a plurality of images in two or more different brightness ranges, and the at least one first processor is configured to execute the instructions to obtain each of the first information and the second information from the images captured in different brightness ranges.
 5. The imaging system according to claim 4, wherein the at least one first processor is configured to execute the instructions to select a non-saturated image in which a pixel value of the second area is not saturated from the images captured in different brightness ranges, and obtain the second information from the non-saturated image.
 6. The imaging system according to claim 1, wherein the at least one first processor is configured to execute the instructions to correct the second information by subtracting a value based on an average value of pixel values of the first area from an average value of pixel values of the second area.
 7. The imaging system according to claim 1, further comprising a display that displays at least one of an iris image and a registered image used for an authentication process of the iris image.
 8. The imaging system according to claim 7, wherein the display displays the iris image and the image captured by the camera, simultaneously or alternatively.
 9. The imaging system according to claim 7, wherein the display highlights at least one of a part corresponding to the second area of the iris image and a part corresponding to the second area of the registered image.
 10. The imaging system according to claim 9, wherein the display is configured to switch between presence and absence of highlighting.
 11. An imaging method comprising: capturing an image of an eye area of a target person by using an image sensor that allows imaging without saturating observed light; obtaining, from the image, a first information about a first area that does not include reflection of light by an eyeglass lens of the target person, and a second information about a second area that includes the reflection of the light; and correcting the second information so as to reduce an influence of the reflection, on the basis of the first information.
 12. A non-transitory recording medium on which a computer program that allows a computer to execute an imaging method is recorded, the imaging method comprising: capturing an image of an eye area of a target person by using an image sensor that allows imaging without saturating observed light; obtaining, from the image, a first information about a first area that does not include reflection of light by an eyeglass lens of the target person, and a second information about a second area that includes the reflection of the light; and correcting the second information so as to reduce an influence of the reflection, on the basis of the first information. 